1. Field of the Invention
This invention relates to a camera having a film counter which indicates the number of unexposed film units remaining in the camera.
2. Description of the Prior Art
Cameras of the type described above are well known and generally include a film counter in the form of a drum having a row of teeth. The teeth are adapted to be sequentially engaged subsequent to a camera operation, e.g., actuation of a shutter release button, so as to index or partially rotate the drum in a first direction to thereby position a different character in alignment with a window in a wall of the camera. The characters, which may appear on the periphery of the drum, may represent a starting point, an end position, and the number of unexposed film units remaining in the camera. Often, a pawl is mounted in operative relation to the drum so as to limit rotation of the drum in a second direction, thus maintaining the drum in its newly indexed position. An example of this type of structure is shown in U.S. Pat. No. 4,212,524. However, it appears that the structure disclosed in the '524 patent does not contain any means for preventing overwinding of the counter drum's return spring. Stated another way, it appears that if one were to continue to actuate the shutter release of the camera after all of the film units had been removed from the film cassette, the counter would continue to be indexed until eventually the counter return spring was overwound. On the other hand, if the structure of the '524 patent does not contain a counter return spring, then it is not apparent how the counter is reset when a film cassette is removed from the camera since this is the function of the return spring.
The aforementioned overwinding problem can be solved by removing or configuring one or more teeth in the row so that the drum cannot be indexed after the last film unit has been exposed, as taught by U.S. Pat. No. 3,653,313. However, in this proposal a second pawl is required. This problem may also be solved by a film counter assembly which utilizes a single pawl, as taught by U.S. Pat. Nos. 4,075,647 and 3,984,852. But, although only a single pawl is used in the systems described in the latter two patents, they both need counter drums having two rows of teeth.